scholarly journals ( R )-Citramalate Synthase in Methanogenic Archaea

1999 ◽  
Vol 181 (1) ◽  
pp. 331-333 ◽  
Author(s):  
David M. Howell ◽  
Huimin Xu ◽  
Robert H. White
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Methanogenic Archaea ◽  
Protein Product ◽  
Methanococcus Jannaschii ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme

ABSTRACT The Methanococcus jannaschii gene MJ1392 was cloned, and its protein product was hyperexpressed in Escherichia coli. The resulting protein was purified and shown to catalyze the condensation of pyruvate and acetyl coenzyme A, with the formation of (R)-citramalate. Thus, this gene (cimA) encodes an (R)-citramalate synthase (CimA). This is the first identification of this enzyme, which is likely involved in the biosynthesis of isoleucine.

scholarly journals Novel Type of ADP-Forming Acetyl Coenzyme A Synthetase in Hyperthermophilic Archaea: Heterologous Expression and Characterization of Isoenzymes from the Sulfate Reducer Archaeoglobus fulgidus and the Methanogen Methanococcus jannaschii

2002 ◽  
Vol 184 (3) ◽  
pp. 636-644 ◽  
Author(s):  
Meike Musfeldt ◽  
Peter Schönheit
Keyword(s):  
Coenzyme A ◽  
Pyrococcus Furiosus ◽  
Sequence Similarity ◽  
Hyperthermophilic Archaea ◽  
Archaeoglobus Fulgidus ◽  
Methanococcus Jannaschii ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Α And Β Subunits

ABSTRACT Acetyl coenzyme A (CoA) synthetase (ADP forming) (ACD) represents a novel enzyme of acetate formation and energy conservation (acetyl-CoA + ADP + Pi ⇌ acetate + ATP + CoA) in Archaea and eukaryotic protists. The only characterized ACD in archaea, two isoenzymes from the hyperthermophile Pyrococcus furiosus, constitute 145-kDa heterotetramers (α2, β2). The coding genes for the α and β subunits are located at different sites in the P. furiosus chromosome. Based on significant sequence similarity of the P. furiosus genes, five open reading frames (ORFs) encoding putative ACD were identified in the genome of the hyperthermophilic sulfate-reducing archaeon Archaeoglobus fulgidus and one ORF was identified in the hyperthermophilic methanogen Methanococcus jannaschii. The ORFs constitute fusions of the homologous P. furiosus genes encoding the α and β subunits. Two ORFs, AF1211 and AF1938, of A. fulgidus and ORF MJ0590 of M. jannaschii were cloned and functionally overexpressed in Escherichia coli. The purified recombinant proteins were characterized as distinctive isoenzymes of ACD with different substrate specificities. In contrast to the Pyrococcus ACD, the ACDs of Archaeoglobus and Methanococcus constitute homodimers of about 140 kDa composed of two identical 70-kDa subunits, which represent fusions of the homologous P. furiosus α and β subunits in an αβ (AF1211 and MJ0590) or βα (AF1938) orientation. The data indicate that A. fulgidus and M. jannaschii contains a novel type of ADP-forming acetyl-CoA synthetase in Archaea, in which the subunit polypeptides and their coding genes are fused.

scholarly journals Repression of Escherichia coli PhoP-PhoQ Signaling by Acetate Reveals a Regulatory Role for Acetyl Coenzyme A

2003 ◽  
Vol 185 (8) ◽  
pp. 2563-2570 ◽  
Author(s):  
Joseph A. Lesley ◽  
Carey D. Waldburger
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Inhibition Mechanism ◽  
Acetate Metabolism ◽  
Dependent Manner ◽  
Two Component System ◽  
Acetyl Coenzyme A ◽  
Component System ◽  
Acetyl Coenzyme ◽  
Two Component

ABSTRACT The PhoP-PhoQ two-component system regulates the transcription of numerous genes in response to changes in extracellular divalent cation concentration and pH. Here we demonstrate that the Escherichia coli PhoP-PhoQ two-component system also responds to acetate. Signaling by the E. coli PhoP-PhoQ system was repressed during growth in acetate (≥25 mM) in a PhoQ-dependent manner. The periplasmic sensor domain of PhoQ was not required for acetate to repress signaling. Acetate-mediated repression of the PhoP-PhoQ system was not related to changes in the intracellular concentration of acetate metabolites such as acetyl-phosphate or acetyladenylate. Genetic analysis of acetate metabolism pathways suggested that a perturbation of acetyl coenzyme A turnover was the cause of decreased PhoP-PhoQ signaling during growth in acetate. Consistent with this hypothesis, intracellular acetyl coenzyme A levels rose during growth in the presence of exogenous acetate. Acetyl coenzyme A inhibited the autokinase activity of PhoQ in vitro, suggesting that the in vivo repressing effect may be due to a direct inhibition mechanism.

scholarly journals Chloramphenicol-Sensitive Escherichia coli Strain Expressing the Chloramphenicol Acetyltransferase (cat) Gene

2001 ◽  
Vol 45 (12) ◽  
pp. 3610-3612 ◽  
Author(s):  
Joanna Potrykus ◽  
Grzegorz Wegrzyn
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Chloramphenicol Acetyltransferase ◽  
Coli Strain ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Cat Gene

ABSTRACT An Escherichia coli strain (strain CM2555) bearing the chloramphenicol acetyltransferase (cat) gene was found to be sensitive to chloramphenicol. We demonstrate that thecat gene is efficiently expressed in strain CM2555. Our results suggest that decreased levels of acetyl coenzyme A incat-expressing CM2555 cells in the presence of chloramphenicol may cause the bacterium to be sensitive to this antibiotic.

scholarly journals Involvement of iclR and rpoS in the induction of acs, the gene for acetyl coenzyme A synthetase of Escherichia coli K-12

2006 ◽  
Vol 146 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Sooan Shin ◽  
Suk Gil Song ◽  
Dae Sang Lee ◽  
Jae Gu Pan ◽  
Chankyu Park
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
K 12

scholarly journals Both Acetate Kinase and Acetyl Coenzyme A Synthetase Are Involved in Acetate-Stimulated Change in the Direction of Flagellar Rotation in Escherichia coli

1998 ◽  
Vol 180 (4) ◽  
pp. 985-988 ◽  
Author(s):  
Rina Barak ◽  
Walid N. Abouhamad ◽  
Michael Eisenbach
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Response Regulator ◽  
Acetate Kinase ◽  
Acetate Metabolism ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Chemotaxis Proteins ◽  
Flagellar Rotation

ABSTRACT Escherichia coli strains overproducing the response regulator CheY respond to acetate by increasing their clockwise bias of flagellar rotation, even when they lack other chemotaxis proteins. With acetate metabolism mutants, we demonstrate that both acetate kinase and acetyl coenzyme A synthetase are involved in this response. Thus, a response was observed when one of these enzymes was missing but not when both were absent.

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